The invention relates to a method for nitriding a component of a fuel injection system, said component being subject to high pressure and being composed of an alloyed steel.
German Laid-Open Application DE 102 56 590 A1 discloses that an injection nozzle of a fuel injection system is very robust if the injection nozzle is in a nitrided state. In this case, corrosion resistance and wear resistance, in particular, are enhanced. However, no details are given of the nitriding method per se in this publication.
WO publication WO 2001/042528 A1 has furthermore disclosed a method for nitriding an injection nozzle. The known nitriding method comprises a nitrocarburizing process in a salt bath in a first step, followed, in a second step, by a gas nitriding process at a temperature between 520° C. and 580° C. with a low nitriding index or low nitriding potential (in a range between 0.08 and 0.5), i.e. in the “a range” of the Lehrer diagram.
The stresses on the components of a fuel injection system carrying fuel under very high pressure—especially in the region of restrictions—can lead to very high cavitation stresses on these components. Even in the case of the components treated by the nitriding methods described above, this can lead to relatively severe cavitation damage.